High-efficiency X-Band MMIC GaN power amplifiers operating as rectifiers

This paper presents a performance evaluation of GaN X-Band power amplifiers operating as self-synchronous rectifiers. Two single-stage MMIC power amplifiers are characterized under continuous wave conditions at 10.1GHz. One PA is designed with a single 10 × 100μm HEMT in a 0.15μm GaN process, while the other contains two 10 × 100μm power-combined devices. The MMICs exhibit 67% and 56% power added efficiency at V_DD = 20V in deep class-AB bias, respectively. In rectifier mode, biased in class-C, the same MMICs show a RF-to-DC efficiency of 64%. The output powers of the two MMIC PAs are around 3.2W. In rectifier mode, the gate DC bias and the load-pull determined RF gate impedance are set for optimal efficiency. The DC load does not affect the efficiency substantially, and can be chosen for a desired voltage or current. The paper demonstrates that high-power efficient GaN rectifiers can be achieved by designing high-efficiency PAs at least up to X-band.